Excel- I didn't know what I didn't know

I have been away for a while so I am trying to make up for some blog posts.  In the class we were given an Excel task to complete.  I went into the assignment fairly confident in my knowledge and ability in using Excel.  As a math teacher I was comfortable in creating formulas and created charts and graphs.  In a previous course I was introduced to some filter and sorting functions that I have never used before.  This assignment introduced me to so much more.  I thought that I was good but felt challenged by some of the tasks like the pivot table.  I had never used one before but was able to work my way through it.   Excel is such a useful tool for so many things, but is not introduced to our students enough.  There are so many jobs in which fluency in Excel is important.  The more students are comfortable with it the more they will and may have to use it.   Sometimes it is necessary to find out things that you didn’t know you didn’t know.  Anybody used Excel for any cool projects in your classes?